src/Tools/Code/code_runtime.ML

--- a/src/Tools/Code/code_runtime.ML	Sun Mar 27 19:27:50 2022 +0000
+++ b/src/Tools/Code/code_runtime.ML	Sun Mar 27 19:27:52 2022 +0000
@@ -302,7 +302,7 @@
               Ts
               |> cons T
               |> fold (fold add_typ o snd) typ_signs;
-        val required_Ts = fold add_typ requested_Ts [];
+        val required_Ts = build (fold add_typ requested_Ts);
         val of_term_for_typ' = of_term_for_typ required_Ts;
         val eval_for_const' = eval_for_const ctxt proper_cTs;
         val eval_for_const'' = the_default "_" o Option.map eval_for_const';